Roller earth-boring drill



Jan. 9, 1923. 1,441,553

H. W. FLETCHER.

ROLLER EARTH Boy: NG DR l LL FILED MAY 25, 1 922.

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HAROLD W. FLETCHER, OF HOUSTON, TEX

- CORPORATION OF- TEXAS.

OF HOUSTON, TEXAS, A

tree

AS, ASSIGNOR T HUGHES TOOL COMPANY;

ROLLER EARTH-BORING DRILL.

Application filed May 25,

To 11]] whom 1'! may concern:

Be it known that l. Ilanou) .W. FLETCHER, a citizen ofthe United States, residing at llouston, llarris County, Texas, have. invented a certain new and useful Improvement in Roller llarth-lioring Drills. of which the following is 2! act description. such as will enable others skilled in the art to which it a-ppertains to make and use the same.

Hy invention relates to an improvement in roller earth boring drills, and has particular application to an improvement in the flushing system which carries away the cuttings from' the drill and serves to exert a pressure upon the lubricating device, whereby the cutters are supplied wit-h lubricant. l

In theordinary typeof roller earth boring drill now in use. the rotar v cutters thereon are lubricated by means of a lubricator secured to the head of the bit and from which oil ducts lead to the bearingsof the cutters. The flushing water which is pumped forcibly downward through the drill stem and the head of the. hit upon the cutters serves to carry away the cuttings insuspension to the surface outside of the drill stem. lt also serves to exert a p res-. sure upon a piston resting on the lubricant and to thereby force the lubricant downwardly to the cutters. An object-ion which sometimes arises in the use of the flushingwater-to operate the lubricating 3:) system is that the 'lorceexerted by the pumps is not steady and continuous and for that reason the pressure upon the h bricator pis l ton is somewhat intermittent and does not result in a steady flow of the lubricant to the cutter bearings. It is an object of this invention to pro vide means whereby the pump pressure in the drill stem will be made steady and uniform so that the feed of lubricant will be also uniform and continuous during the operation of the drill.

Referring to the drawing herewith Fig. 1 a central longitudinal section through a. drill stem and lubricator showing the use of my-invention, and Fig. 2 is a transverse section on the plane 2-2 of Fig. 1.

l have shown my improvement .as attached to a drill ordinarily used in cutting rock. It has a head 1 having conical shaped tull. clear, and ex 1922. Serial No. 563,b68.

cutters 2 on the forward end thereof. The upper end of the head is reduced in diameter and threaded at 3 for attachment by means of a drill collar 4 to the drill stem 5. At the central upper end of the head is a further reduced bank (3 threaded exteriorly to provide attachment for a lubricator collar 7. This collar is tapered somewhat and threadedat the upper end at 8 for attach-x ment-to a coupling 9 by means of which it is connected to the lubricator barrel 10.

The lubricator collar "7 is recessed at its lower end to receive the shank 6 of the bit and also to provide attachment for a valve seat 11 screwed therein. Said valve seat has a central passage therethrough threaded on the lower side for attachment to a pipe 12 constituting awvater course for the flushingfiuid. The head of the drill is formed with a central channel 13 therethrough to receive the water course. The upper, end of the valve seat is reduced in diameter and fitted within a chamber 14 inthe lubricato'r collar. Above the chamber 1- 1 the-said collar is provided with a central cylindrical reeess or counterbore 15 to slidably receive a valve 16. This valve is cylindrical on its outer surface to fit the recess 15 and is tapered at. its lower end to fit within the valve seat 1? formed in the upper end of the member 11. Said valve is formed with.

a central bore 18 enlarged at 19 at its upper end.

The chamber 14 adjacent the valve is termed with three upwardly inclined water channelslll to allow passage for the fiushing water downwardly to the cutters.

The coupling 9 has a central reduced passage 21 therethrough, adapted to be closed by a rotary valve 22 of ordinary construction. The .lubricator barrel 10 is closed at the upper end by means of a plug 23, this plug being provided with passages 2 t tlierethrough to permit theentrance of flushing water to the upper end of the lubricator barrel. An opening 25 diametrically through the pliig 23 and the barrel of the lubricator ftorms a seat'for a cotter pin or other similar means to secure the said plug in position in the lubricator barrel. Below the said plug is a piston 26 having cups 27 thereon fittingfiuid tight against the inner walls of the barrel. The said piston is adapted to rest on the upper surface of the A ia lubricant and will be forced down by the pressure of the flushing fluid against the lubricant, driving it outwardly.through the passage 21 in the coupling 9 and into a corresponding passage 28 in the upper end of the lubricator collar 7. At the lower end of the passage '28 are ducts 29 leading to an annular channel 30 formed in the lower face of the lubricator collar. This channel ex tends entirely around the upper shank of the bit and is connected by means of the oil ducts 31 to the bearings of the cutters which are to be lubricated.

In the operation of my device the flushing fluid will be pumped downwardly through the drill stem to the bit and will find a passage through the openings 20 in the lubricator collar to the valve chamber 14. Pressure of the flushing fluid upon the lower tapered surfacecf the valve 16 will force it upwardly out of its seat and allow the flusl'iing Water to pass downwardly througlr the water course 12 to the cutters. The greater the pressure of the water within the valve chamber the higher the valve will be lifted by the pressure of the water and the larger will be the opening permitted for the ge of the water into the water course. ii 'efore, when the pressure is high the wa ls cou e will be open approximately to its full mi, so that this pressure will be relieved. rem-however, the pressure tends to drop in the drill stem the pressure in the valve chamber will also drop, allowing the valve 3.6 to partially close the opening in the valve seat 17. T his will tend to back up the pressure in the drill stem and to increase the amount of pressure exerted upon the piston in the lubricator chamber. It is obvious that, with the weight of the valve 16 properly adjusted, the said valve will serve to relieve the pressure when it tends to build up beyond a certain desired point, or will tend to close and thereby build up the pressure when the pressure would otherwise tend to fall. The action of the valve will thereby be practically automatic in its regulation of the pressure in the neighborhood of the lubricator: The opening 18 in the valve allows the passage from the chamber above the valve of the fluid which might tend to gather there and prevent the free action of valve. y

The advantages of this pressure-regulating valve lie largely in the uniform water pressure obtained within the drill stem, whereby the piston may be forced with a fairly constant and uniform pressure upon the lubricant. The flow of the lubricant to the beurings will therefore be uniform.v By adjusting the weight of the valve the pressure necessary to the proper feed of lubricant can be maintained regardless of the speed of the pumps. V

Having thus described my invention what I claim as new and desire to protect by Letters Patent is:

'1. In a roller 'eartluboring drill, a drill head. rolleucutters thereon, a lubricutor collar on said drill, a fluid passage through said collar and drill head, a valve seat in said passage, a valve in said seat having a tapered lower end. the upper end beinp slidable into a recess in said collar, a lubrisaid passage, an upwardly opening valveslidable in said head and adapted to be raised from its seat by a predetermined pressure of the fluid, a lubricator on. said collar actuated by the pressure of said fluid and connections between said lubricator and the bearings of said cutters.

In a roller earth boring drill, a drill stem, a head thereon having roller cutters secured thereto, a passage through said head for flushin fluid, an upwardlyopening valve in said passage, said valvehaving a tapered lower surface, the upper end being slidablein a recess in said collar, whereby a predetermined fluid pressure downwardly through the passage will. raise said valve, and a fluid-pressure-operated lubricator on said head having connection with the bearings of said cutters.

4. In a. roller earth boring drill, a drill stem, a drill head thereon, rolling cutters on said head, a passage from said drill stem through said head for flushing fluid, a valve seat in said passage, a valve therein of larger diameter than the passage through said seat,-

the upper end of said valve being slidable in a recess, whereby a predetermined fluid pressure will raise said valve from its seat, a, fluid pressure operated lubric'ator on said head and passages from said lubricator to the bearings of said cutters. i s

5. In a roller earth boring drill, a drill stem, at head thereon, rolling cutters on said head, a passpge for flushing fluid through said head fro m said drill stem, a lubricant container on said head having channels leading therefrom to the bearings of'said cutters, fluid pressure operated means to force said i lubricant from said container, and meane t-n said fluid passage to maintain said fluid pres sure automatically to a predetermined amount. In testimony whereof. I hereunto aflix In signature, this the 20th day of May, A. D1, 1922.

HAROLD W. FLETCHER. 

